Circadian Expression of Adiponectin and Its Receptors in Human Adipose Tissue

Adiponectin isoneof themostclinically relevantcytokinesassociatedwithobesity.However, circadian rhythmicity of adiponectin in humanadipose tissue (AT) has not been analyzed. To assesswhether the mRNA levels of adiponectin and its receptors (ADIPOR1 and ADIPOR2) might show daily circadian rhythms in visceral and sc fat explants obtained frommorbid obesewomen, visceral and sc abdominal AT biopsies (n 6) were obtained from morbidly obese women (body mass index 40 kg/m2). An-thropometric variables were measured and fasting plasma glucose, lipid, and lipoprotein concentra-tions were analyzed. To investigate rhythmic expression pattern, AT explants were cultured during 24 h, and gene expression was analyzed at the following times: 0800, 1400, 2000, and 0200 h, using quantitative real-time PCR. All genes investigated showed a circadian rhythmicity and oscillated ac-curatelyand independentlyof the suprachiasmaticnucleus inbothATexplants (P0.05).Adiponectin geneexpressionfluctuatedinthesamephaseas its receptors.Correlationanalysesbetweenthegenetic circadian oscillation and components of the metabolic syndrome revealed that adiposity and abdominal obesity correlatedwith a decrease in adiponectin and adiponectin receptorsADIPOR1 andADIPOR2 am-plitude(P0.05).VisceralfatshowedatrendtowardaphasedelayanddampeningofthemRNAamplitude ofadiponectinascomparedwithscfat.ThemRNAexpressionofadiponectinanditsreceptorsshowed24-